1. Field of the Invention
The present invention relates to a lens barrel and an imaging apparatus.
2. Description of the Related Art
There has been proposed an imaging apparatus including a non-circular focus lens. For example, Japanese Patent Laid-Open No. 2010-54783 discloses an imaging apparatus in which at least a portion of the outer periphery of a focus lens is in a non-circular shape and a guide shaft is disposed within a void space.
FIG. 7 is a view showing the configuration of a rear focusing unit provided in the imaging apparatus disclosed in Japanese Patent Laid-Open No. 2010-54783. In FIG. 7, a first lens frame 3 constituting a rear focusing unit is shown. On the first lens frame 3, a lens 3f for the first lens frame, a nut 3a, a nut holding unit 3b, a guide shaft A4c, a guide shaft B4d, a loosely fitting hole 3e for a guide shaft B, a guide shaft A-receiving portion 3d, and a lead screw 4b are provided.
The lens 3f for the first lens frame has a substantially elliptical shape. The long side diameter of the lens 3f is “b” and the short side diameter thereof is “c”. Specifically, the lens 3f has two notches that are formed by cutting out the outer periphery of the circular-shaped lens. The guide shaft A4c and the guide shaft B4d are provided in these notches.
However, in the imaging apparatus disclosed in Japanese Patent Laid-Open No. 2010-54783, a guide shaft is disposed within a void space that is produced by bringing a portion of an outer periphery of a focus lens into a non-circular shape, and thus, a drive source for driving the lens cannot be disposed within the space. Thus, the drive source is disposed at an outer position than the outer periphery of the lens. Consequently, the drive source cannot be efficiently laid out within the barrel of the imaging apparatus, resulting in an increase in the diameter of the barrel.